This invention relates to oscillation motors useful to deflect, scan, interrupt or chop beams of light, electrons or other streams of matter with little mass.
Conventional oscillation motors having torsion shaft-mounted rotors suffer numerous disadvantages: the rotors have limited excursion; their resonant frequency drastically decreases as their amplitude of excursion increases; when mounted at the end of a long torsion bar the rotors and accompanying mirrors or other devices are sensitive to cross motion and undesirable oscillations when subjected to mechanical vibrations or accelerations; and the motors operate at a very high Q factor and are generally difficult to tune.
Another problem of such electromagnetic motors, where the rotor is mounted on a flexible shaft, is that the electromagnetic forces which apply the operating torque to the rotor also behave as a second order spring in the radial direction of the rotor, tending to bend the rotor out of its desired symmetrical operating position relative to the stator. Reduction of the electromagnetic forces to reduce this displacement correspondingly penalizes the torque capability of the motor.